GI and applied equine parasitology Flashcards
Is the risk of colic increased or decreased if on a worming program?
Decreased
Is the risk of colic increased or decreased after anthelmintic administration?
Increased
Which parasite was once responsible for up to 90% of colic cases?
Strongylus vulgaris
How does strongylus vulgaris infections lead to colic?
- Thrombosis of the cranial mesenteric artery
- Non-strangulating infarction
Why is Strongylus vulgaris less of an issue now?
Modern anthelmintics
Describe post-worming colic
- This is recognised following anthelmintic treatment of horses known to have high worm burdens
- Inflammation of the GIT subsequent to death of large numbers of parasites
What are the clinical signs of Cyathostominosis?
Weight loss
Hypoalbuminaea
Diarrhoea
Which two types of intussusceptions can occur due to cyathostominosis?
Caecocaecal
Caecocolic
Name the tapeworm species of horses
Anoplocephala perfoliata
Anoplocephala perfoliata is associated with which 3 conditions in horses?
- Spasmodic colic
- Ileal impaction
- Caecal intussusception
Name the ascarid spp of horses
Parascaris equorum
What are the signs and conditions caused by Parascaris equorum?
Weight loss
Unthriftiness
Small intestinal obstruction
Colic
Name the pinworm of horses
Oxyuris equi
How does Oxyuris equi affect horses?
Can cause peri-rectal irritation (tail rubbing)
Some clinical cases can be difficult to treat
What parasite is often an incidental finding when performing gastroscopy?
Gastrophilus intestinalis
Describe the general signs of worm infestations in horses
- Most horses tolerate worm burdens with little outward sign
- Problems often only apparent when clinical disease imminent
- Problems usually associated with high levels of infection
- Therefore emphasis is on CONTROL of parasite levels to prevent risk of disease
What are the aims of parasite control in horses?
To reduce transmission of the parasite thus preventing high levels of parasite infection, therefore reducing the incidence of disease
Name 4 anthelmintics that can be used in horses
Ivermectin
Moxidectin
Pyrantel
Fenbendazole
How can the need for anthelmintic treatment be reduced?
Appropriate stocking density
Pasture management
Target treatments: Use diagnostics
Describe pasture management for reducing the need for anthelmintics
Faecal collection – at least twice a week
Dung heaps separate from grazing areas
Pasture rotation
Grazing with ruminants
Be aware that parasites can overwinter on pasture
Describe how Cyathostomins are diagnosed
- Faecal egg count for adult stages
- Small redworm blood test
Describe how Anoplocephala perfoliata are diagnosed
- FEC: centrifuge flotation
- ELISA: herd level testing of horses
- EquiSal: saliva based test
Foals are most at risk from which parasites?
Ascarids
Strongyles
Tapeworms
Describe Parascaris equorum disease in foals
- Migrating larvae cause respiratory disease
- Patent infection is a common cause of colic
How is Parascaris equorum treated?
Not with anthelmintics
Heavily contaminated pasture poses a risk
The risk of Strongyle infection in foals is dependant on?
The level of exposure to a large infection
FEC to check exposure
How is a Strongyle infection treated in foals?
Autumn/winter moxidectin treatment
When is a tapeworm infection in foals treated?
If risk of high level of exposure may need treatment in older foals (>6 months)
Use Saliva or ELISA test to assess risk
Describe a common control practice for parasites in foals
2-3mo foal - Fenbendazole treatment (around May/June)
4-5mo foal - Fenbendazole (July time)
7-8mo foal - Fenbendazole (September time)
Moxidectin treatment in November (Strongyle risk)
Fenbendazole for Parascaris spp
The majority of clinical larval Cyathostomin cases are at what age?
1-3yo
Young stock are at risk of which parasites?
Strongyles
Tapeworms
At what age do horses have their highest FECs?
When they are young stock
Describe the considerations for control of parasites in youngstock
- FEC should be conducted more frequently
- Important to ensure efficacious drugs used
- Prioritise clearing of pastures on which youngstock are grazing: at least twice a week
- Grazing practices to reduce pasture contamination are very important in management of youngstock
Describe how diagnostics should be used incorporated into parasite control in youngstock
Tapeworm ELISA/Saliva test
Cyathostomin larval test
Treatments given need to be based off diagnostic tests
Describe the treatment of parasites in youngstock
It may be necessary that youngstock (>6.5 months) are given moxidectin and praziquantel in autumn, if management is poor a second treatment is recommended 3 months later
When is the period of risk for larval cyathostominosis?
October - March
Describe parasite management in adults
Don’t just rely on drug treatment
Use FEC to target drug treatments
Many horses will shed few eggs onto pasture
Describe how treatment is targeted in adult stock
Treatment targeted at those animals with moderate to high FEC to reduce pasture contamination
Which age group is at the least risk of disease due to parasites?
Adults
Describe the test and treat philosophy for adult horses
- FEC reduction tests should be performed annually
- If the risk to the population is high then more frequent FECs should be carried out
List the factors which indicate a low risk of parasitic infection in horses
- Repeated negative FEC/tapeworm antibody levels
- Between 5-15yo
- Faecal collection >2x a week
- Good pasture management
- Stable population
- Low stocking density
- No youngstock
- Effective quarantine
- No history of parasitic disease
- No history of colic
List the factors which indicate a high risk of parasitic infection in horses
- High FEC/antibody levels
- Less than 5yo
- No faecal collection
- Poor pasture management
- Transient population
- High stocking density
- Grazing with youngstock
- No quarantine
- History of parasitic disease
- History of colic
List the factors which indicate a moderate risk of parasitic infection in horses
- Low/moderate FEC/antibody levels
- More than 15uo
- Sporadic faecal collection
- Moderate pasture management
- Occasional movement
- Medium stocking density
Describe the quarantine procedures that can be used to reduced the risk of parasites
- FEC + other diagnostics on new stock
- Moxidectin-Praziquantel (PRAMOX) combination usually recommended as quarantine treatment
- House for ~3 days to eliminate shedding of eggs post treatment
Describe Parascaris anthelmintic resistance
No studies in the UK, but has been reported
IVM-resistance is most common
Benzimidazole and Pyrantel drugs remain effective BUT resistance is emerging to these drugs
Describe Strongyles/Cyathostomin anthelmintic resistance
- Resistance to MLs is now apparent
- BZs ineffective on all yards
- PYR effective on <50% studs
- IVM/MOX effective on many studs but resistance is now evident
- Resistance to IVM/MOX requires further investigation
How is Oxyuris equi controlled?
Drugs, washing of peri anal region and environment requires power cleaning
How is Oxyuris equi diagnosed?
Adults in faeces
Eggs in perianal region
